Leveling is the process of determining the elevation of a point relative to another point. The curvature of the Earth and atmospheric refraction affect the result of leveling. There are techniques and formulas to correct the effect of Earth’s curvature and atmospheric refraction.

Flat-Earthers assume that construction works like roads, bridges, railways, etc. are built without accounting for Earth’s curvature. They are wrong. The leveling in such works are done in such a way it minimizes the errors due to Earth’s curvature and atmospheric refraction.

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Curvature Dilemma

A ship disappearing from the bottom first is an effect of Earth’s curvature. It is not a direct observation of the curvature itself. We can only directly see the curvature from a significant altitude, not from near the surface.

Flat-Earthers present this reality as if it is a dilemma: 1. Earth is too big for us to see the curvature, but 2. We can see ships go over the curvature. It is a false dilemma. Ships disappearing from the bottom first is an effect of Earth’s curvature. Witnessing such an effect of Earth’s curvature is different from witnessing the curvature itself.

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Axiological Analysis

The shape of the Earth can also be determined from the axiological standpoint. If knowledge of a particular shape of the Earth has many applications we use every day, while the other has none, then we can be sure the one with many applications is the correct shape of the Earth.

There is absolutely no technology that depends on the supposed ‘knowledge’ that the Earth is flat. On the other hand, there is plenty of technology we use every day that depend on the understanding that the Earth is a sphere. And therefore, we can be sure that the Earth is a sphere.

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Earth Globe

An Earth globe is a spherical model of Earth with similar purposes to maps, but unlike maps, do not distort the surface that they portray except to scale it down. The Greeks from the 3rd century BC knew Earth is a sphere, and the earliest globe appeared from that period.

Flat-Earthers take the appearance of a globe before NASA existed as a sign of misconduct, like Universal Studios logo from the 20s. They incorrectly claim that it should not be possible to know Earth is a sphere before the first spaceflight. In reality, we knew spherical Earth since 3rd century BC and globes were already commonplace far before the first spaceflight. In fact, the success of spaceflight depends on our understanding of the spherical shape of the Earth.

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The Moon and Stars in a Single Picture

Stars are not visible in photos of the Moon –including those taken from the lunar surface— because the Moon is sunlit. The exposure needed to take a photograph of the Moon is not that much different from that used to take a photo in daylight on Earth’s surface.

To demonstrate this, we can try taking a picture of the Moon with stars visible, on the conditions: 1. The lunar features, like the craters, are correctly exposed, not overexposed. 2. Taken in a single exposure, not HDR, and not the result of editing. Even if we are using the best camera available today, the stars can’t show up in large enough quantity.

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Buzz Aldrin’s Interview & the Quote-Mining by Flat Earthers

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In September 2015, Buzz Aldrin gave an interview at the National Book Festival in Washington, D.C. Flat-Earthers misrepresented and quoted it out of context as if Buzz was admitting that the Apollo Moon landings never happened.

The original interview was 17 minutes long, and there were other occasions Buzz clearly said the Moon landings happened, without any possibility of misinterpretation.

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High-Altitude Nuclear Explosions (HANE)

High-altitude nuclear explosions (HANE) are the results of atomic weapons testing, conducted by the United States and the Soviet Union between 1958 and 1963. In these tests, nuclear warheads were launched and deliberately detonated at a high altitude, between 23 km and 540 km.

Flat-Earthers claim that HANEs were produced by attempts to penetrate the mythical dome enclosing the supposed flat Earth using nuclear weapons. They are wrong. The warheads were deliberately detonated at a high altitude, and the mythical dome does not exist in reality, only in their imaginations.

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Shell Theorem

Shell theorem is a simplification stating that a spherical body affects external objects gravitationally as though all of its mass were concentrated at a point at its center.

The direction of Earth’s gravity toward the center of the Earth made some flat-Earthers to assume that we think gravity is caused by something in the center, and that our inability to go there “disproves” gravity. They are wrong. Earth’s gravity is the result of the entire mass of Earth. Using the center of the Earth is merely a simplification.

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Nikola Tesla was not a Flat Earther

Nikola Tesla was a genuine physicist, engineer, and inventor. He knew very well that the Earth is a rotating sphere, gravity exists, stars are very far, planets are not stars, etc.

Flat-Earthers often claim Nikola Tesla as their own, as if he believed in a flat Earth. These claims are quickly proven wrong by merely reading some of Tesla’s writings. It is obvious from his writings that he was not a flat-Earther.

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Zooming-In on the Setting Sun

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Camera zoom works by enlarging the center portion of the image, or in other words, by making its field-of-view narrower. Zooming in on the setting sun will not reveal more of the sun, and will only enlarge the size of the sun in the resulting image.

Flat-Earthers are claiming that zooming in on a setting sun will reveal the entire sun, and somehow lift it out of the water. They are wrong. They simply used the incorrect exposure settings. In reality, zooming on the setting sun will never reveal the sun that is already obstructed by Earth’s curvature.

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Appeal to Definition

The fallacy of ‘appeal to definition’ is using the definition of a term to support an argument as if the term cannot have other meanings or even conflicting meanings. Flat-Earthers often use this fallacy, for example, over the word “theory.”

A communication problem can occur when a term gets misinterpreted to mean other than what was intended. A simple clarification should quickly correct the problem. The appeal to definition arises if the clarification is refused, and the person insists on using the wrong & unintended meaning of the term, and use it to support their arguments.

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A seismometer is an instrument that responds to ground motions, such as caused by earthquakes, volcanic eruptions, and explosions.

Seismometers are sensitive but they cannot detect Earth’s motion. Flat-Earthers use this to ‘prove’ the Earth is stationary. They are wrong. A seismometer is mounted on Earth’s surface and is already moving at the same speed as the surface itself. It can only detect motion if there is a change in speed —or an acceleration— exerting a force to the seismometer.

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False Analogy in the Use of Scale Models in Flat-Earth “Experiments”

Flat-Earthers like to use scale models to represent an actual object. They would apply the facts they observe from the model to the actual object itself. It is the fallacy of false analogy. The two situations can be substantially different. Just because both the scale model and the real object looks the same, it does not mean they are similar in another aspect.

Observation of the real object is stronger evidence than any argument from analogy —like using a scaled-down model of the real object. Using an analogy to dismiss the result of direct observation of the real object is unreasonable.

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Vacuum in Space and Earth’s Atmospheric Retention

The Earth retains an atmosphere because gravity pulls air particles toward the center of the Earth. Without something affecting the air —like gravity— air particles would move toward lower pressure, and Earth would lose its atmosphere.

Flat-Earthers claim that Earth should not be able to have an atmosphere because without any barrier separating Earth’s atmosphere and space, it would have been sucked by the vacuum in space. They are wrong. Gravity pulls air and allows Earth to retain an atmosphere.

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News Satire

News satire is a type of parody presented in a format typical of mainstream journalism. Some satirical news outlets use satirical commentary to comment on actual, real-world news; while others offer wholly fictionalized news stories.

Satirical news outlets have produced some “reports” mocking the flat Earth belief. Unfortunately, some flat-Earthers failed to realize the satirical nature of the “news,” and that the “news” was created to mock them. Because they think it was real news, the “news” spreads in flat-Earth communities as hoaxes.

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A railgun is an experimental weapon that uses electromagnetic force to launch high-velocity projectiles. Some railguns are expected to have a range of more than 200 miles.

Flat-Earthers claim that a railgun round always travels straight. And because it can hit targets beyond 200 miles, they use it as “proof” Earth’s curvature does not exist. They are wrong. In reality, railgun rounds are projectiles. The same law of physics that applies to bullets, arrows, or thrown rocks also applies to them. The rounds are affected by air resistance and Earth’s gravity, and will not travel straight for very long. Railguns are capable of hitting targets obstructed by Earth’s curvature and are not proof that Earth’s curvature does not exist.

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Laser Guidance

Laser guidance is used by the military to guide a missile toward a target.  A laser designator marked a target by pointing a laser beam at it. The signals bounce off the target into the sky, where they are detected by laser-guided munition, which steers itself toward the center of the reflected signal.

A laser-guided missile can be launched toward a target behind Earth’s curvature. Flat-Earthers claim it proves a flat Earth as it would have been impossible for the launcher to point a laser beam at the target. They are wrong. The laser designator does not have to be the launcher itself. It can be another unit closer to the target, such as infantry or an aircraft.

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Ad Fidentia

The fallacy of ad-fidentia is committed when someone attacks the opponent’s self-confidence instead of the argument or the evidence.

Scientific method is an empirical method of acquiring knowledge, which is an iterative, cyclical process through which information is continually revised. Flat-Earthers would often question their opponents if they are 100% sure about their claims. If we admit there is a possibility we are wrong or that our claims might be revised in the future, flat-Earthers will use that to ‘prove’ us wrong.

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Measurement Error

Measurement error (also called observational error) is the difference between a measured quantity and its true value. A measurement error is not a mistake. Variability is an inherent part of the results of measurements and the measurement process.

Flat-Earthers often point out at ranges of quantities, errors in measurement results, varying results in different attempts of measurement, as well as highlighting the adjectives ‘about’ and ‘approximately’; then present them as ‘proof’ that science does not know it for certain. They are wrong. Any measurement has an error, and it can never be eliminated.

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